Filed Apr. 28, 1970, Ser. No. 32,650 Claims priority, application Japan, May 27, 1969, 44/ 49,761 Int. Cl. D01d 3/00 US. C]. 1885 C 5 Claims ABSTRACT OF THE DISCLOSURE An apparatus for spinning a large number of sheathcore type bicomponent fibers from a single spinnerette is disclosed which comprises a spin dope distribution assembly, immediately adjacent the outlet surface of said assembly an orifice plate, and spaced therefrom, a spinnerette plate arranged in a manner wherein a first spin dope upon emerging from said orifice plate emerges through aligned orifices in said spinnerette plate and a second spin dope upon emerging from said orifice plate travels laterally in the spacing provided and emerges as a sheath around said first spin dope.

BACKGROUND OF THE INVENTION Composite fibers of the type formed by bonding together two fiber-forming components differing in thermal shrinkage in a side-by-side relationship throughout the entire length of the fibers are well known. Such fibers are widely used because of their high desirable crimping and dyeing characteristics. Numerous spinnerette assemblies for forming such bycomponent fibers have been de veloped.

It is also known that large differences in thermal shrinkage between the components forming side-by-side type bi-component fibers although desirable as a result of extensive crimping tendencies, tend to cause separation of the two components, thus destroying the bicomponent fiber. In an effort to avoid separation of fiber components and to achieve the desirable properties associated with large differences in thermal shrinkage between the components, it has been suggested that the components be arranged in a sheath-core relationship. Such an arrangement employing as sheath-forming component a polymer having excellent dyeability and esthetic appeal and as coreforming component a polymer having excellent physical properties such as strength, elongation, and rigidity would lead to a composite fiber improved to a greater extent in both crimping tendencies and performance characteristics than is possible with side-by-side type bicomponent fibers. However, any spinning apparatus for forming such sheathcore type bicomponent fibers is generally so much more complicated than spinning devices for side-by-side bicomponent fibers than the number of fiber-forming orifices per unit area of spinnerette is greatly restricted, such restriction resulting in many instances in a tenfold or greater decrease in the number of fiber-forming orifices per unit area of spinnerette. Such restriction causes a substantial reduction in productivity and, as a result, production of sheath-core type bicomponent fibers has not yet reached a practical stage, particularly in wet-spinning techniques which make use of large numbers of fiberforming orifices per unit area of spinnerette to commercial advantage.

The present invention provides a novel apparatus for spinning a large number of sheath-core type bicomponent fibers per unit area of spinnerette, the apparatus involving Patented Oct. 19, 1971 ice SUMMARY OF THE INVENTION This invention relates to an apparatus for spinning a large number of sheath-core type bicomponent fibers from a single spinnerette. More particularly, the invention relates to such an apparatus comprising a conventional spin dope distribution assembly having adjacent to the discharge face an orifice plate and, spaced therefrom, a spinnerette plate in an arrangement where core-forming spin dope is discharged through orifices in the spinnerette plate aligned with orifices in the orifice plate and sheathforming spin dope is forced to travel in a lateral direction upon exit from the orifice plate and unite as a sheath around the core-forming dope on discharge through the same orifices in the spinnerette plate through which coreforming spin dope is being discharged.

The apparatus described can be readily constructed to contain a large number of fiber-forming orifices per unit area of spinnerette for economic advantage, particularly for wet-spinning techniques, and at the same time satisfies requirements of excellent operation in continuous spinning processes and of simple construction characteristics. Although the device has been particularized with respect to wet-spinning techniques, it is, of course, to be understood that it is equally adaptable to melt-spinning and dry-spinning techniques.

The apparatus may be constructed from a variety of materials conventionally employed in the construction of related devices. Suitable materials include metals and plastics that have suitable structural strength and resistance to chemicals and operating conditions encountered in the spinning processes. In some instances structural metals, such as stainless steel, are preferred, while in other instances, where low heat conductivity is desirable, use may be made of various plastic materials, such as cured epoxy resins. In still further instances, it may be desirable to employ a mixture of structural materials, fashioning some elements from one material and others from another. It is to be understood that the invention is not limited to any particular structural material but only to the particular structural arrangements indicated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially exploded view of the apparatus of the present invention showing an arrangement of various elements used in a specific embodiment of the invention.

FIG. 2 is a sectional view of the apparatus showing an arrangement of dope feed chambers, orifice plate, spacing, and spinnerette plate, also showing the projection of some orifices of the orifice plate on the back of the spinnerette plate and the provision for grooves encompassing such projections.

FIG. 3 is a plane view of the back surface of the spinnerette plate showing a flow pattern for spin dope which emerges from orifices in the orifice plate not aligned with orifices in the spinnerette, said fiow pattern being in the spacing between the orifice plate and the spinnerette plate.

FIG. 4 also is a plane view of the back surface of the spinnerette plate which in this embodiment has grooves forming the sides of a rectangle and shows the flow pat tern of the spin dope in such instance.

FIG. is a cross-sectional view of a fiber formed by the apparatus wherein the flow pattern of spin dope is as illustrated in FIG. 3.

FIG. 6 is a cross-sectional view of a fiber formed by the apparatus wherein the flow pattern of spin dope is as illustrated in FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENTS The invention will now be described with particular reference to the drawings wherein numbering of parts is consistent in the various drawings.

In FIG. 1, that portion of the assembly which excludes parts numbered 6-10, inclusive, is similar to the vertical stack spin dope distribution assembly described in US. Pat. 3,501,805, issued Mar. 17, 1970 to Douglas et al., except that recesses in the plates of the patent corresponding to plate 4 of FIG. 1 of the present application have been eliminated, a necessary elimination due to the dilferent nature of the fiber type being spun.

In FIG. 1 of the present application, end plate 1 is provided with four orifices 17, 18, 17, and 18 which are used to introduce spin dope into the apparatus. End plate 2 is generally similar to end plate 1 except that orifices 17 and 18 are not provided therein. The stack of plates is next composed of a plurality of different plates having diiferent functions arranged in a definite sequence. Each plate is provided with orifices 17, 18, 17 and 18 which, when the plates are assembled in the form of the stack, line up with the corresponding orifices 17, 18, 17 and 18 in end plate 1 to provide four spin dope passageways leading through the stack from end plate 1 to the last plate prior to end plate 2.

Adjacent end plate 1 in the stack there is a first plate 3 with openings 12 leading from orifices 1-8 to the flat upper surface of the stack. Thus, first plate 3 provides a pathway for spin dope from the first group of passageways 18, 18 through openings 12 to the surface of the stack. Note that passageways 17, 17 are isloated from openings 12 and therefore there is no communication by way of first plate 3 between the second group of passageways 17, 17 and the surface of the stack.

Temporarily skipping the next plate in the stack, we find that the next plate after it is a second plate 5, which, preferably, may be the mirror image of first plate 3 and, as such, may be manufactured as a plate identical with first plate 3 but inserted into the stack in a reversed position. Second plate 5 is provided with openings 11 which communicate between orifices 17, 17 and the same surface of the stack as do openings 12 in plate 3'. Note that orifices 18, 18 in plate 5 are isolated from openings 11. Thus, second plate 5 provides a pathway for spin dope between the second group of passageways 17, 17 through openings 11 to the surface of the stack.

Between first plate 3 and second plate 5 is interposed at third plate 4, which serves to separate openings 12 from openings 11 in the adjacent plates 3 and S. The stack then continues with plates in the following order in a repetitive pattern: after second plate 5 comes another third plate 4, then another first plate 3, then another third plate 4, then another second plate 5, and so on for whatever number of plates may be desired before reaching end plate 2.

The various plates making up the stack are fastened into an integral structure by means of any suitable fastening materials. Generally, additional bolt holes are pro vided at several points through the various plates of the stack and the stack is secured by bolts passing through the provided bolt holes.

The orifice plate 8 is of a size coinciding with the upper surface formed by the joined plates of the stack, i.e. the surface to which spin dope flow has been directed. It is provided with a plurality of orifices in rows which are aligned with the flow pathways for spin dope provided by plates 3 and 5. The spacing or orifices 10 in any one row is halfway between orifices in the adjacent row.

A spacing plate 7 is placed immediately above orifice plate 8 to provide clearance necessary for lateral fiow of spin dope containing the sheath-forming component of the bicomponent fiber to be spun.

Above spacing plate 7 is placed spinnerette plate 6. Spinnerette plate 6 contains a plurality of fiber-forming orifices 9 arranged in rows which are aligned with orifices of the orifice plate through which flows spin dope containing core-forming component of the bicomponent fiber to be spun.

Orifice plate 8, spacer plate 7, and spinnerette plate '6 are laminated and secured to the surface of the stack to which flow of spin dope is directed.

The arrangement of fiber-forming orifices 9 of the spinnerette plate 6 is such that they align only wit-h those orifices 10 of the orifice plate 8 through which flows spin dope containing core-forming component of the bicomponent fiber to be spun. Additional orifices 10 of orifice plate 8 occupy four corners of a rectangle having the aligned orifices 10 and 9 centrally located therein. This arrangement is best seen in FIG. 3 which shows the back face of spinnerette plate 6*. In FIG. 3, the aligned orifices are indicated as double circles and the single circles represent projections 10' of additional orifices 10 of orifice plate 8 upon spinnerette plate 6. The arrows in FIG. 3 indicate the flow pattern of spin dope striking projections 10 under the influence of the operating pressure of the spinning apparatus, such flow occurring in the spacing between orifice plate 8 and spinnerette plate 6.

The sectional view in FIG. 2, left side, indicates alignment of orifices 10 and fiber-forming orifices 9 and also indicates location of projections 10' on spinnerette plate 6.

In operating the apparatus as just described, a spin-dope containing core-forming component is introduced through the passageways of the vertical stack which flow spin dope through orifices 10 in orifice plate 8 which are aligned with fiber-forming orifices 9 in spinnerette plate 6. A second spin dope containing sheath-forming component is introduced through the other passageways. As the second spin dope emerges from orifices 10 of orifice plate 8 it strikes against projections 10' on the back face of spinnerette plate 6 and is forced by operating pressure into flow patterns illustrated in FIG. 3 into the spacing between orifice plate 8 and spinnerette plate 6 to form a sheath about the core-forming component as it emerges from fiberforming orifices 9. In the operation described, the flow patterns of spin dope strikng projectons 10 on the back face of spinnerette plate 6 is such as to cause flattening on four sides of spin dope containing core-forming component with the result that the bicomponent formed will have the cross-section shown in FIG. 5.

An additional modification of the present invention is the invention for grooves 19 on the back face of spinnerette plate 6. The positioning of grooves 19 on the back face of spinnerette is shown in FIG. 2;, right side, which shows grooves 19 as rounded depressions in the area in which the projections 10' would normally be shown. In FIG. 4, the grooves are shown to form the sides of a rectangle which has as its corners the normal projections 10' of orifices 10 of orifice plate 8 on spinnerette plate 6 and the aligned orifices 10 and fiber-forming orifices 9, represented as double circles, are centrally located in said rectangle. The arrows in FIG. 4 illustrate a flow pattern of spin dope entering into grooves 19. The flow patterns illustrated in FIGS. 3 and 4 differ because grooves 19 control the flow of spin dope normally striking projections 10' to the point where spin dope from several projections meet and overflow the grooves. Accordingly, when the operation of the apparatus is carried out in the manner previously described except for the provision of grooves 19 in the arrangement shown in FIG. 4, the formed bicomponent fiber has the cross-section shown in FIG. 6.

It can be readily appreciated that by suitable variation in the depth, width, and direction of grooves 19 on the back face of spinnerette plate 6, a wide variety of crosssections of the formed bicomponent fiber is possible. Additional variations can be achieved by displacement of orifices 10 of orifice plate 8 that are not aligned with fiberforming orifices 9 of spinnerette plate 6.

Although in the embodiment illustrated by FIG. 1, use is made of a spacer plate 7 to provide spacing between orifice plate 8 and spinnerette plate 16, it can be readily appreciated that other embodiments are possible which can eliminate need for spacer plate 7. For example, spacing can be provided by projections from orifice plate 8 or from spinnerette plate 6 or from both.

An additional spin-dope distribution assembly that can be employed in conjunction with the orifice plate. and spaced spinnerette plate in the present invention is de scribed in US. Pat. 3,245,113, Sulich, issued Apr. 12, 1966, and represents a horizontal stack type.

We claim:

1. An apparatus for spinning a large number of sheathcore type bicomponent fibers from a single spinnerette comprising a distribution assembly having stacked dope feed chamber plates defining therebetween flow passageways having outlet surfaces for two separate fiber-forming spin dopes, an orifice plate immediately adacent said outlet surfaces, and, spaced therefrom, a spinnerette plate with fiber-forming orifices, wherein said fiber-forming ori fices are disposed in rows above the flow passageway of the stack which feeds one of the two dopes, the orifices in said orifice plate are disposed in rows such that (a) one set of rows is directly above the flow passageway for one dope with each orifice aligned with a corresponding fiberforming orifice in said spinnerette plate and (b) another set of rows is directly above the flow passageway for the second dope with the orifices therein disposed halfway between orifices of said first set whereby the dope flowing through said first set of orifices of said orifice plate forms the core-forming component of said fiber and the other dope is directed by lateral flow through the space provided to emerge as the sheath-forming component of said fiber.

2. The apparatus of claim 1 wherein said distribution means is a vertical stack type.

3. The apparatus of claim 2 wherein the back of said spinnerette plate is provided with grooves which direct flow of said sheath-forming component.

4. The apparatus of claim 1 wherein said distribution means is a horizontal stack type.

5. The apparatus of claim 4 wherein the back of said spinnerette plate is provided with grooves which direct flow of said sheath-forming component.